Pintle or poppet valves are well known. For example, it is known to provide a pintle valve between the exhaust manifold and the intake manifold of an internal combustion engine for recirculating a portion of the engine exhaust into the intake air stream. Such a valve is known in the art as an exhaust gas recirculation (EGR) valve.
An EGR valve comprises two basic component groups: a valve group itself and an actuator group. Typical EGR valve actuators include solenoids, torque motors, stepper motors, and DC motors. The actuator, coupled with an appropriate driver, moves the valve group to a desired position based on commands from an engine control module (ECM). The actuator group also typically includes a position feedback sensor that monitors the position of the valve group and provides position feedback to the ECM so that the ECM can adjust its commands to the actuator accordingly. This closed-loop control system operates continuously while the engine is running to provide the correct amount of recirculated exhaust gas under all engine operating conditions.
Different size engines and/or different emission regulations require different flow capabilities from an EGR valve system. Some known EGR valves have single-poppet valve groups, wherein one poppet lifts off of one seat to allow exhaust gas to pass. Single-poppet valve groups in general have excellent sealing capability. Other known EGR valves have dual-poppet valve groups to meet very high flow requirements. Dual-poppet valve groups are known in the art generally to have rather poor sealing capability because it is very difficult to have both poppets make contact with their seats at the same time and with the same force.
Prior art dual-poppet valves have both poppets fixed to a common pintle shaft, and both valves open in the same direction. For both poppets to seal properly, the poppet spacing on the pintle shaft must be exactly the same as the spacing between the valve seats. In practice this is virtually impossible to achieve, so that, in closing, one or the other poppet will strike its own seat first, and the other poppet will be thus prevented from sealing against its own seat with the same degree of closure.
What is needed in the art is a dual-poppet valve capable of high flow but also capable of optimal sealing, like a single-poppet valve.
It is a principal object of the present invention to provide a high flow dual-poppet valve wherein both poppets seal fully in the closed position.